Performance assessment of thermochemical CO2/H2O splitting in moving bed and fluidized bed reactors. (23rd August 2021)

• Record Type: Journal Article
• Authors: Farooqui, Azharuddin; Angal, Prudwee; Shamim, Tariq; Santarelli, Massimo; Mahinpey, Nader
• Is Part Of: International journal of hydrogen energy. Volume 46:Number 58(2021)
• Page Start: 29774
• Page End: 29794
• Publication Date: 2021-08-23
• Subjects: Moving bed reactor -- Fluidized bed reactor -- Solar fuels -- Chemical looping -- Reaction kinetics -- CO2/H2O splitting; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2021.06.141
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: In this paper, we present the assessment of moving bed reactors and fluidized bed reactors operating in different fluidizing regimes for solar thermochemical redox cycles (STRC) for syngas production. The reduction reactor with a moving bed (MBRED ) while the oxidation reactor (OXI) is either a moving bed reactor (MBOXI ) or bubbling bed (BBOXI ) yields higher performance. It was observed that only water splitting is suitable at 1400 °C and 10 −3 bar reduction conditions. The higher reduction temperature and pressure improved the efficiency of the CO2 /H2 O splitting unit. The requirement of the H2 /CO ratio drives the gas feed (CO2 /H2 O) into OXI. To achieve an H2 /CO ratio of 1, MBOXI and BBOXI require an equimolar mixture of CO2 and H2 O at 1600 °C. However, to achieve a similar H2 /CO ratio at a lower temperature of 1500 °C, the gas feed of the CO2 /H2 O ratio required is 3. A similar H2 /CO ratio is achieved for OXI operating in a turbulent and fast fluidizing, but the selectivity is lower due to lower reaction rates. OXI as a transport bed is least suited based on solid conversion (XOXI ), H2 /CO, or efficiency. The results are useful in designing the redox reactors for syngas. Highlights: Moving bed and fluidized bed regimes are investigated for CO2 /H2 O splitting. Bubbling regimes yield similar selectivity of moving bed but require 4 reactors. CO2 /H2 O: 0.75/0.25 is suitable for the H2 /CO ratio ~1.0 for 1600 °C and 10-7 bar. For TRED and PRED of 1400 °C and 10-3 bar the only H2 O splitting is suitable. The CL efficiency was highest for moving bed reactors for reduction and oxidation.